This invention relates to a positioning and turning apparatus.
Positioning and turning arrangements of this type make it possible to improve and facilitate manipulation of large workpieces, especially for metallic arc welding, and herein, especially to provide access to large workpieces and the alignment of such workpieces in preferred positions, such as, for instance, the trough position in welding. These developments have been limited in regard to receiving capacity, construction size and precision, thereby preventing not only operational efficiency, but also, most importantly, a breakthrough to greater automation.
It is, therefore, an object of the invention to provide a positioning and turning apparatus of the aforementioned type in such a way that it will make it possible to handle large loads of workpieces at reasonable construction costs, while at the same time making exact, sensitive adjustment in workpiece positions possible so that even heavy and large workpieces can be dealt with in automatized work processes, such as, for example, by means of computerized positioning.
It has been found that an especially weak feature of the bearing support mounting arrangement exists at the turning joints, and above all, in the turning joint between the stand and carrier. With increasing loads, the traditional mounting support over two shaft bearings arranged at an axial distance from each other required constantly larger distances and/or bearing support capacities, wherein however, precision requirements and the oscillating stability and constancy of the system could be increasingly less controlled. These oscillation problems affected the arm in regard to bending stress as also in regard to torsional stress, wherein the latter rendered the sensitivity of the setting or adjustment as well as the flow of the starting oscillation process unacceptable.
Also corresponding problems arose on the mounting of the positioning plate, although they were mainly dependent on position and of a relatively smaller magnitude.
A switching of the herein described type of mounting in only one bearing plane of large diameter leads to concepts in construction which allow making the stand much more compact, especially in the longitudinal direction of the carrier. Seen from the perspective of construction, besides greater compactness of the positioning plate, this also allowed for a different formation of breaking through the supporting surface with a ring formation of the positioning plate, making thus difficult or not-at-all accessible areas on the workpiece accessible. As an alternative regarding compactness, the possibility arises of a constructional stiffening for removing the oscillation sensitivity of the system and, also with increasing diameter of the bearing, the possibility of substantially reducing the side effects of bearing play in the axial as also in the radial direction.
Herein the large diameter provided by the bearing can at the same time be taken advantage of for setting and blocking rotation in order to achieve high sensitivity and precision. Thus the carrying side portion of the support bearing in the stand as also the plated side portion of the plate bearing at the carrier end can be connected to a toothed wheel or ring gear whose large radius results in exactness and sensitivity if a worm gear or similar device exercises control from the stand or the carrier.
This precision also represents a breakthrough for the application of automatized adjusting or setting methods, especially in combination with positional control devices and/or digital controls.
It is particularly advantageous that the positioning and turning apparatus has at least one adjustable carrier operable with the positioning plate for receiving the workpiece and the ring bearing at the end of the carrier. It is particularly advantageous if two adjustment carriers, arranged cross-wise in the form of a cross carrier are used. Thus, it is not only possible to bring the workpiece into every desired angle position but also to move it translatorily in the corresponding angle position. Furthermore, it is thus possible to move the workpiece in relationship to the ring bearing on the carrier so that it is moved opposite to the axis of the ring bearing. For highly accurate machining, for example in the case of welding of workpieces, the workpiece is then able to make the desired movements, while the tool--in the case of welding, the welding torch--is stationary. It has been shown that it is difficult in many cases to perform precise and non-oscillating movements with a tool suspended over a long arm or ceiling structure. In contrast, the positioning and turning apparatus allows very accurate working movements, particularly in the case of automated machining processes, eliminating the problems concerning inaccuracies and oscillation. It has also been shown that it is more favorable to move the workpiece and leave the tool stationary even if the workpiece is much heavier than the tool. The stable and precise support is of advantage when moving the workpiece while a comparable stable suspension of the tool would be exceedingly complicated.
Additional characteristics and advantages of the invention are disclosed in the claims and the subsequent description which include the objects of the invention and an embodiment illustrated by means of drawings.